Recent evidence shows that innate lymphoid type 2 cells (ILC2s) through production of IL-13 and IL-5 are critical in airway pathologies and tissue damage, strongly correlated with severe asthma. ILC2s not only produce IL-5 and IL-13, but also the epidermal growth factor amphiregulin, which promotes tissue remodeling and lung homeostasis following influenza infection. For developing therapeutic strategies to specifically target ILC2-mediated inflammation, while maintaining tissue repair activity, it is of crucial importance to delineate regulatory mechanisms involved in ILC2 development, maintenance and function. Our preliminary data demonstrate that Bcl11b is highly expressed in ILC2 cells in the periphery, as well as in bone marrow precursors. Induced removal of Bcl11b causes loss of their identity. Bcl11b-/- ILC2 population showed reduced IL-5 production following papain-induced lung inflammation, resulting in diminished eosinophil and increased neutrophil recruitment to the lung. Additionally, numbers of ILC2s were overall reduced in the bone marrow. In this grant application we propose to establish the role of Bcl11b in ILC2s lineage determination, in mature ILC2 cell function and identity and determine the mechanisms by which Bcl11b controls ILC2 genetic program.